INDEX• OVERVIEW• 3D DISPLAY TECHNIQUES With Glasses • ANAGLYPH • POLARIZATION • ECLIPSE METHOD• 3D DISPLAY TECHNIQUES Without Glasses • GUIDED LIGHT • LENTICULAR SCREEN • PARALLAX BARRIER• OBSTACLES
OVERVIEWHUMAN VISION & PERCEPTION OF 3D WORLD• Human eyes are equipped with an absolutely amazing binocular vision system. For objects up to about 20 feet (6 to 7 meters) away, the binocular vision system lets us easily tell with good accuracy how far away an object is.• The binocular vision system relies on the fact that our two eyes are spaced about 2 inches (5 centimeters) apart. Therefore, each eye sees the world from a slightly different perspective, and the binocular vision system in our brain uses the difference to calculate distance. Our brain has the ability to correlate the images it sees in its two eyes even though they are slightly different.
PRINCIPLE OF 3D DISPLAY• Main concept behind 3D display is to generate a sense of variation in depth. To achieve this, two perspective of a single image, each for one eye, is used. The principle is to send an individual image to each eye. our eyes can correlate these images automatically because each eye sees only one of the images.
3D TECHNIQUES WITH GLASSESANAGLYPHIn this system, two images are displayed on thescreen, one in red and the other in blue (or green).The filters on the glasses allow only one image toenter each eye, and our brain does the rest.DRAWBACK: We cannot have a color movie whenwe are using color to provide the separation, so theimage quality is not nearly as good as with thepolarized system.
3D TECHNIQUES WITH GLASSESPOLARIZATIONTwo synchronized projectors project tworespective views onto the screen, each with adifferent polarization. The glasses allow only one ofthe images into each eye because they containlenses with different polarization.DRAWBACK: Its very difficult to use thepolarization technique for home theater systems --most methods would require to coat our televisionscreen with a special polarizing film first.
3D TECHNIQUES WITH GLASSESECLIPSE METHOD:Liquid crystal shutter glasses are used in conjunction with a display screen.Each eyes glass contains a liquid crystal layer which has the property ofbecoming dark when voltage is applied, being otherwise transparent. The glasses are controlled by an infrared, radio frequency that sends atiming signal that allows the glasses to alternately darken over one eye, andthen the other, in synchronization with the refresh rate of the screen.
PROBLEMThe most common 3D displays requireusers to wear special glasses, whichhas limited the technology’spopularity. Now researcher andvendors are working on glasses-free3D displays.
SOLUTIONUsing auto stereoscopic displays togenerate 3D images without glasses.
AUTO STEREOSCOPIC DISPLAY There are two broad classes of auto stereoscopic displays: 1). Multi view 2). Light field
MULTIVIEW A multi view display uses optics to render two or more views of a scene, which the user’s optical system fuses into single 3D image
LIGHT-FIELD Light field displays generate pixel-like elements that transmit image-brightness data and information about the direction and angle that light rays would travel from an object to a viewer’s eyes. This makes it easier for the optical system to interpret the image properly.
3D TECHNIQUES WITHOUT GLASSESGuided light:This techniques usespecial holographicprisms that organizemultiple high endprojectors output into asingle 3D image.
3D TECHNIQUES WITHOUT GLASSESLenticular sheetThis method relies on a display coatedwith a lenticular film. Lenticuler are tinylenses on the base side of a special film.The screen displays two sets of the sameimage. The lenses direct the light from theimages to our eyes -- each eye sees onlyone image. Our brain puts the imagestogether and interpret it as a three-dimensional image.
3D TECHNIQUES WITHOUT GLASSES• Parallax barrier:• A parallax barrier is a device placed in front of an image source, such as a liquid crystal display, to allow it to show a stereoscopic image without 3D glasses. Placed in front of the normal LCD, it consists of a layer of material with a series of precision slits, allowing each eye to see a different set of pixels, so creating a sense of depth through parallax in an effect similar to what lenticular printing produces for printed products.
OBSTACLES• Because they entail complex projection and display technologies, auto stereoscopic system cost substantially more than traditional 3D displays.• To render multiple viewing angles for a group of users, lenticular and barrier techniques lose resolution.• Moreover they offer a limited number of viewing angles from which users can see 3D images.